Refrigerating apparatus



Mal- 23,1943. 5. A. mwmm' 2.314.591

REFRIGERATING APPARATUS Filed June 20,1940 2 Sheets-Sheet 1 14- I [5L4- [p18 52 15 11 36 p ATTORNEY8..

' INVENTOR.

March 23,1943. A. A. mcoRm'AaK RERRIGERATING APBARATUS 2 Sheets-Shee 2 Filed June "'20; 1940 immediately before Patented Mar. 23, 1943 Alex A. McCorniack; Dayton,

Ohio, assignor to General Motors Corporation; Daytornohio, a

corporation of Delaware Application June 20,1940, Serial No. 341,516

11 Claims.

This invention relates to refrigerating apparatus and more particularly to an unloading means for a refrigerant compressor.-

- An object of this invention is to provide an unloader which will unload the, compressor in a relatively short time but which will not materially reduce the efiiciency of the compressor during the normal operating cycle.

Another object of this invention isto provide an, unloader which requires no moving parts and which does not depend upon the presence'of lu-.

bricant for controlling the unloading of the compressor.

Still another object of this invention is to provide an unloaderwhich is simple and inexpensive and which may beadded to any conventional sealed compresssor unit without disturbing the arrangement or construction of the in- .ternal mechanism of the unit.

Inasmuch as electric current failures of-very short duration frequency occur which make it necessary for the compressor motor to restart the,unloader has had time and a discharge denser unit Iii. The compressed ga's fiows 1 of the drawings, the hermetically sealed motorcompressor-condenser unit, generally designated by the reference character ill comprises a rotary compressor unit l2 driven by an electric motor having a rotor l5 and a stator I! provided with the usual form of starting and running-windings. The compressor l2 may be of any conventional design and is provided with an intake l5 l8 through which compressed refrigerant is discharged directly 'into'the lower casing section 20 of the motor-compressor-confrom the lower casing section 20 through an aperture 22 into the upper casing section 24. The compressed gas flowing through the opening 22 flows upwardly between the. motor rotor I5 and the motor stator H. The compressed refrigerant vapor is condensed in the space occupied byv the .water' coil 28. Condensing water is supplied suitable source through arged through the outlet heat conducting fins to the coil 26 from anthe inlet 28 and is disc 30. While I have not shown in contact with the water coil, 26, the effective to unload the compressor, it is an object of this invention to provide anelectric overload device which serves to momentarily cut off the supply of current to the motor for a period of time which is substantially equal or slightly greater than the time required for the unloading device I to unload'the compressor. I A further object of this invention is to'provide means for unloading the compressor without completely equalizing the entire high side with the entire low side of the refrigerant system] A still further object of this inventionis to provide an unloader which is suitable for use in a compressor in which the lubricant is under high side pressur and in which the high side pressure is depended upon or cant to the places requiring lubrication.

Further objects and advantages of the present invention will be apparent from the following description, referencwbeing had to the accom-' panying drawings, wherein a preferred form of the present invention is clearly shown. In the drawings:

In Fig. 1 I have shown a preferred arrange ment; p

Fig. 2 is an elevational view with-parts broken away of a modified form of unlo'ader;

Fig. 3 is a sectional view taken on line of Fig. 2; and Y Fig. 4 is a view similar to Fig. 2 showing a further modification. In the preferred arrangement ing means evaporated prior to its return to the compressor forcing the lubri- I v 0 tom of the chamber condensing surface of the coil- 26 may be increased by providing additional heat radiating surfaces in thermal contact.therewith.

Th condensed ity formed between the casing 24 and the motor stator I! from whence the liquid refrigerant flows through the outlet 32 to a pressure reduc- 34 which may be of any well-known design, preferably of the fixed restrictor type in which the refrigerant is caused to flow through a'r'e'latively long passage of small cross section. The refrigerant leaving the restrictor 34 enters the evaporator 36- in which the refrigerant is via the vapor line 38.

An unloading chamber Q0 has been provided 38 adjacent the. intake of the compressor. As shown in Fig. l, the suction lin 38 enters the chamber 40 adjacentthe top thereof and is provided with a check valve l2 which allows flow of refrigerant from the line 38 5 into the chamber. 40 but whichprevents the flow of refrigerant from the chamber back into the line 38. A strainer element 44 mounted in the chamber 40 is adapted to separate out any dirt particles from the refrigerant. At the botlil is provided an outlet pip 48 which'is connected to the intake of the compressor and which also is provided, with a check valve 48 which allows the free fiow of refrigerant from the chamber .401 into the compressor but shown in Flash which checks the fiow'ofrefrigerant and larefriger'ant collects in the cav- 40. Any conventional form of check valves may be used for this purpose. A supply of lubricant 50 is provided in the casing section 20. This supply of lubricant is subjected to the high side refrigerant pressure and is supplied to the compressor through the bottom wall of the compressor in the usual well-known manner. By virtue of the pressure differential existing between the casing 20 and the intake of the compressor a small amount of lubricant tends to flow into the compressor during the off-cycle periods. Some lubricant might even back up into the suction pipe 46 were it not for the check valve 48. In order to simplify this disclosure the details of the compressor and the lubricant feed means have been omitted as these details are well known to those skilled in the art and may take on various well-known forms.

In order to equalize the pressure at the outlet of the compressor with the pressure at the inlet of the compressor, I have provided a small capillary tube 52 which has its inlet 54 arranged to I enter the main compressor casing at a point where the compressed gas is in a superheated state. The outlet of the capillary tube 52 is arranged to extend into the unloading chamber 40. The amount of restriction in the capillary tube 52 is designed so as to permit the necessary equalization of pressure between the inlet and the outlet of the compressor in a period of approximately three minutes.

before the compressoris required to pump against any appreciable pressure difference.

The motor starting circuit and current overload protector, generally designated by the reference character 56, areof the type which is fully shown and described in connection with Fig. 2 of- Pearce Patent No. 2,018,896, to which reference is hereby made for a more complete description of the function and operation of the starting and unloading circuits. The overload device is so constructed as to stop the flow of .current to the motor at such times when the load on the motor is too great to allow the motor to start. The time required for the overload device to reclose the motor circuit after having cut out because of an overload is made sufilciently long to allow the capillary tube unloader 52 to unload the compressor. While I have described the unloader 52 as being capable of unloading the compressor in a period of approximately three minutes, it

- is apparent that the period of time required for the unloader 52 to perform its function and the overload device 35 to perform its function may both be varied.

In Fig. 2 I have shown a slightly modified arrangement of an unloader in which the external chamber 40, shown in Fig. 1, hasbeen omitted and in which an internal toroidal-shaped cham-. ber 10 has been provideddirectly within the upper portion of the casing 24. In this modification the suction line 38 leads directly to the check valve 48 provided at the inlet to the compressor. A separate passage comprising the tube I2 has been provided directly between the unloading chamber I0 and the compressor inlet. The upper end of the tube "terminates adjacent the top of the chamber 10. A capillary unloader tube 14 is provided which has an inlet 16 arranged in the superheated portion of the compressor dome and an outlet 18 in the chamber 10. Inasmuch as no check valve is provided in the line 12 between the inlet to the compressor and the chamber 10, some The size of the chamber 40 is such' that the compressor may make several revolutions I lubricant may find its way into the passage I2 and may actually enter the chamber 10. In order to prevent lubricant which may have collected in the chamber 10 from all returning to the compressor when the compressor first starts up, a

small opening has been provided in the tube 12 adjacent the bottom of the chamber 10 whereby only a slow stream of lubricant will enter the passage 12 from the chamber 10 when the compressor begins operating. For purposes of illustration. the passage 12 has been shown as being arranged partly on the outside of the motor-compressorcondenser housing whereas it is apparent that the passage 12 may be arranged completely within the outer casing, if desired. Except for the differences in the unloading mechanisms, the systems shown in Fig. 1 and Fig. 2 are similar and like reference characters have been used to designate like parts. In the modification'shown in Fig. 4, an unloading chamber has been provided which functions in much the same manner as the chamber 10 in Fig. 2 functions. In this modification an unloader capillary tube 92 is provided which has an inlet 94 arranged within the upper portion of the motor-compressor-condenser dome 24-and has an outlet 88 arranged within the unloading chamber 90. In this modiflcation a pipe 98 communicates directly with the intake of the compressor and terminates at I Ill adjacent the top of the unloading chamber 80. Inasmuch as no check valve is provided .in the passage leading from the compressor intake to the unloading chamber 90, a certain amount of lubricant may tend to back up into the unloading chamber through the passage 98. In order to prevent this lubricant from being supplied too rapidly to the compressor when the compressor first starts up, a small opening I02 is provided between the passage 98 and the unloading chamber 90 which serves to restrict the flow of lubricant from the unloading chamber to the compressor intake when the compressor first starts up.

It is to be understood that the motor-compressor-condenser units disclosed in Figs. 2, 3 and 4 are of the same general construction as the motorcompressor-condenser unit disclosed in Fig. 1 and may be provided with-the same electrical controls including the same type of electric overload protector.

While the-form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow. A

What is claimed is as follows:

1. In combination, an evaporator, a compressor having an inlet and anoutlet, a condenser, first refrigerant flow means between saidcondenser and said evaporator, second refrigerant flow means between said evaporator and said compressor, refrigerantfiow means between said compressor and said condenser, a chamber in said second refrigerant flow means, means preventing the flow of'refrigerant from said chamber to the outlet of said evaporator, means preventing the fiow of refrigerant from the inlet of said compressor to said chamber, and means said passage arranged to allow free flow of gas from the unloading chamber to the compressor inlet but preventing return flow of gas, and a capillarytube extending from the compressor outlet to said unloading chamber.

3. In combination, a compressor having an inlot and an outlet, a casing enclosing the compressor and providing a high pressure chamber surrounding the compressor and into which the compressor discharges, and means for establishing communication between said. chamber and the inlet of said compressor at all times, said last named means comprising an unloading chamber and a capillary tube connected in series.

4. In combination, an evaporator, a comprcssor, a condenser, refrigerant flow connections between said evaporator, compressor and con-- denser, a casing enclosing said compressor, an unloading chamber within said casing, means providing an unrestricted passage between said ing system comprising a receptacle adapted to be connected to the suction side of a compressor. means for introducing refrigerant vapor and lubricant into said receptacle comprising means having a first opening into the upper portion of said receptacle and a second smaller opening communicating with the lower portion of said receptacle, and means forming a passage joining said receptacle with the high side of said refrigerating system.

8. In a refrigerating system, a casing, motorcompressor-condenser means sealed within said casing and adapted todischarge high pressure unloading chamber and the inlet of said compressor, and means providing a restricted passage between the outlet of said compressor and said unloading chamber, said restricted passage comprising a relatively long capillary tube of small internal diameter.

5. In combination. an evaporator, a compressor, a condenser, refrigerant flow connections between said evaporator, compressor and con-- denser, a casing enclosing said compressor, an unloading chamber within said casing, means providing an unrestricted passage between said unloading chamber and the inlet of said compressor, and means providing a restricted passage between the outlet of said compressor and said unloading chamber, said restricted passage comprising a relatively long capillary tube of small internal diameter, said first-named passage having a main opening into said chamber adjacent the top of said chamber and a restricted opening into said chamber adjacent the bottom of said chamber.

6. In a refrigerating system, a compressor hav-- ing suction and discharge connections, a condenser, an evaporator, a fixed restrictor, means connecting said compressor, condenser, evaporefrigerant flow passage leading from said casing' to said unloading chamber, said unloading chamber comprising a second casing mounted exteriorly of said first-named casing and enclosing a plurality of convolutions of small diameter tubing forming a portion of said restricted flow passage.

, 10. In combination, a compressor having an,

inlet and an outlet, means into whichv the compressor discharges, and means for establishing communication between said means and the inlet of said compressor, said last named means comprising an unloading chamber and a capillary tube connected in series.

11. In combination, an evaporator, a compressor, a condenser, refrigerant new connections between said evaporator, compressor and condenser, an unloading chamber, means providing rator and fixed restrictor in series refrigerant I flow relationship, and compressor unloading means comprising means forming an unloading chamber associated with the suction side of said compressor and a capillary tube joining said unloading chamber and the discharge side of said compressor.

7. An unloading device for use in a refrigeratan unrestricted passage between said unloading chamber and the inlet of said compressor, and means providing a restricted passage between the outlet of said compressor and said unloading chamber, said restricted passage comprising a relatively long capillary tube of small internal diameter.

ALEX A. McCORMACK.

suction side of 

